Name: finding voltage and impedance in circuit a
Uploaded: 2025-05-22T09:06:14.000Z
Duration: 1 min 18 s
Channel: JoVE

包括配电线路和变压器在内的家庭电力分配系统，可以被视为源网络。
在房屋内部，各种电器设备可以表示为负载阻抗。
戴维南定理将这个复杂的配电系统简化为一个戴维南等效电路。
求戴维南等效电路需要知道两个参数：戴维南电压和戴维南阻抗。
为了理解其确定过程，可考虑一个连接至电压源的简化 RLC 电路。
计算戴维南阻抗时，将电压源替换为短路，并确定电路的等效阻抗。
戴维南电压等于开路电压，相当于电路中并联支路的电压降。
首先，计算流经电路闭合网孔的电流。然后根据欧姆定律，确定并联支路上的电压降，该电压即为戴维南电压。
如果电路中的电源在不同频率下工作，则必须针对每个频率分别确定戴维南等效电路以及电容和电感的阻抗。

戴维南等效电路

Th&#233venin Equivalent Circuits

在家庭配电系统中，包括配电线路和变压器，都是主要的网络部分。家庭内的电器可以用负载阻抗来进行表示。为了能够简化这个复杂的分配系统，可以使用戴维南定理来建立出戴维南等效电路。如果交流电路分为两部分（电路 A 和电路 B），那么便可以通过一对端子来进行连接，如图1所示。 <img alt="Figure1" src="/files/ftp_upload/15113/15113_PT_Figure_1.svg" style="text-align: center; height: 140px;"> 图1：电路分为两部分 <img alt="Figure2" src="/files/ftp_upload/15113/15113_PT_Figure_2.svg" style="text-align: center; height: 150px;"> 图2：电路 A 被其戴维南等效电路取代

用戴维南等效电路（与阻抗串联的电压源）来替换电路 A，则不会改变电路 B 中任何元件内的电流或电压（如图2所示）。无论电路 B 是否会连接到电路 A 或者其戴维宁等效电路，电路 B 中所有电路元件内的电流值和电压值都将会是相同的。寻找戴维南等效电路的过程中需要两个参数：戴维南电压和戴维南阻抗。图3显示了连接在电路 A 端子上的开路，以此来确定开路电压 Voc，而图4则表明了戴维南阻抗 Zt 是电路 A* 中的等效阻抗。

<img alt="Figure3" src="/files/ftp_upload/15113/15113_PT_Figure_3.svg" style="text-align: center; height: 96px;">

图3：戴维南等效电路与 Voc。

<img alt="Figure4" src="/files/ftp_upload/15113/15113_PT_Figure_4.svg" style="text-align: center; height: 96px;">

图4：显示 Zt 的戴维南等效电路。。 电路 A* 是由电路 A 通过将所有独立的电压源替换为短路并将所有独立的电流源替换为开路而形成的。一般情况下，戴维南阻抗 Zt 可以通过反复用等效阻抗来代替串联或并联阻抗来进行确定。

家庭电力配电系统，包括配电线路和变压器，构成主要网络。家庭内部的电器设备……

Education

教育

JoVE Core

Electrical Engineering

电气工程

Unit 1

第一单元

AC Circuit Analysis

交流电路分析

KEY TERMS AND CONCEPTS

关键术语与概念

finding voltage and impedance in circuit a

The household power distribution system can be simplified with Thevenin's theorem. In this system, distribution lines and transformers form the main network. Electrical appliances can be treated as load impedance, which makes the circuit easier to analyze.

An AC circuit can be split into two parts, circuit A and circuit B, with a single pair of terminals between them. Circuit A can then be replaced by its Thevenin equivalent circuit. That equivalent has a voltage source in series with an impedance.

Replacing circuit A with its Thevenin equivalent does not change the current or voltage of any element in circuit B. The values in circuit B stay the same whether it is connected to the original circuit A or to the Thevenin equivalent. This is why the method is useful for studying connected circuits.

Two values are needed to build the Thevenin equivalent circuit. The first is the Thevenin voltage, which is found from the open-circuit voltage across the terminals of circuit A. The second is the Thevenin impedance, Zt, which is the equivalent impedance of circuit A*.

To form circuit A*, all independent voltage sources are replaced with short circuits. All independent current sources are replaced with open circuits. Then series or parallel impedances can be combined repeatedly to find Zt.

Finding Voltage and Impedance in Circuit A

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phasors

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AC Circuit Phasors: Resistor, Inductor, Capacitor

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AC Circuit Rules with Phasor Diagrams

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Series and Parallel Impedance Rules

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th&#233venin equivalent circuits

The household power distribution system can be simplified with Thevenin's theorem. In this system, distribution lines and transformers form the main network. Electrical appliances can be treated as load impedance, which makes the circuit easier to analyze. An AC circuit can be split into two parts, circuit A and circuit B, with a single pair of terminals between them. Circuit A can then be replaced by its Thevenin equivalent circuit. That equivalent has a voltage source in series with an...

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key terms and concepts

Learn how Thevenin's theorem simplifies household AC circuits by using open-circuit voltage and equivalent impedance to model circuit A.

Finding Voltage and Impedance in Circuit A | JoVE K12

JoVE Core Electrical Engineering offers easy-to-understand animated videos that cover fundamental concepts of electric circuits along with circuit analysis techniques. It incorporates first-order and second-order circuits using operational amplifiers and circuit transformation concepts. The inclusion of practical design examples and real-world applications through scientist-in-action videos adds significant educational value, making complex concepts accessible.

electrical engineering

Finding Voltage and Impedance in Circuit A

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